1. Field of the Invention
The invention relates to novel, crosslinkable, elastic compositions, a process for their preparation, and their use as casting compositions and for the production of mouldings. The applications of these compositions are extremely versatile. They include joint sealants, adhesives, putties, knifing fillers and vibration-damping compositions.
2. Discussion of the Background Art
The prior art reveals crosslinkable, elastic compositions which are obtained by mixing hydroxyl group-containing polybutadienes with various crosslinking agents and which are used, for example, as cable jointing compositions. Also taught are processes in which carboxyl group-containing polybutadienes are reacted with epoxides (see DE-OSS 22 57 053 and 27 41 453). As the catalyst, tertiary amines are frequently used (see DE-OSS 21 40 949 and 22 05 209). In the context of this invention, "elastic compositions" are to be regarded as being compositions whose elongation value is at least 10%.
Although the known compositions satisfy some important applicational requirements, namely that they can be mixed to a high proportion with fillers and can be crosslinked at various temperatures in a relatively short or relatively long time, they still, however, have the following disadvantages:
1. There are toxicological doubts about some components of these compositions, such as epoxides and diisocyanates, since the compositions are frequently prepared by untrained personnel and misuse cannot be excluded.
2. Some crosslinking systems are not sufficiently reactive. The consequence is, in some cases, very long crosslinking times. This objection applies, for example, to the compositions which are described in European Patent 0,049,098 and which comprise an epoxy resin and a maleated polybutadiene.
3. Although the compositions described, for example, in DE-OS 34 36 556 are prepared from toxicologically acceptable components, they do not always enable flawless moulding. This applies, in particular, to use at low temperatures.
Irrespective of these observed disadvantages of the known compositions based on functionalized polybutadienes, it must be ensured that no cleavage products are produced during the subsequent cross-linking reaction. No shrinkage may occur during crosslinking and, finally, homogeneous crosslinking should occur, even in the absence of oxygen and solvents.
There have been numerous attempts to improve the properties of compositions of this type based on polybutadiene by developing newer crosslinking agents. However, a completely satisfactory solution has not been found.